Automatic fire alarm



Aug, 14, 1934 c. E. CQLE ET AL AUTOMATIC FIRE ALARM Filed Oct. 27, 1953 L, E- [,0 INVENTORS E. Marrw on BY V .5 i qa bez 6 ATTORNEYS Patented Aug. 14, 1934 AUTOMATIC FIRE ALARM Clifford E. Cole and Earl Morrison, Birmingham, Ala., and Isaac V. Sigsbce, Peoria, 111., assignors to J. T. Hufistutler, Birmingham, Ala.

Application October 27, 1933, Serial No. 695,442

6 Claims.

Our invention relates to automatic fire alarms, more particularly to that class of alarms which embodies a bi-metallic member adapted to bend I and form an electric contact under the influence 6 of heat. It has for its object the provision of such a fire alarm which shall be simple of construction, easy to manufacture, and which shall include means for providing a double contact in response to a rise in temperature. v A still further object of our invention is to provide an automatic fire alarm embodying heat responsive elements wherein a double scraping electric contact is made when the heat responsive members move when subjected to heat.

A still further object of our invention is to provide an automatic fire alarm embodying bimetallic members movable in response to heat, together with an improved protective housing for I the members whereby they may not readily be fouled by dirt or otherwise upon remaining inactive over long periods of time.

We have found in the construction of automatic fire alarms in which an electric contact is made and a circuit completed for ringing a gong or other alarm apparatus, that it is a prime essen-. tial that such circuit closing devices be so con! structed that they may not readily be fouled when left. unattended over a long period of time.

It often occurs that such systems may be installed in a building and not be called upon to function for many years. Under such circumstances, there is an inevitable accumulation of dust and dirt on the contact memberswhich might prevent the completion of the circuit depended upon to eiiect the alarm. It is accordingly desirable in designing such apparatus that the contact members be protected as much as possible from accumulation of dirt and dust and also be free to respond to a rise in temperature caused by a fire. It is furthermore essential that the contact membersbe so constructed as to operateeven with a considerable accumulation of dirt and dust. r

q The above and other objects which will become apparent from a reading of this specification are accomplished by means of our invention which compri fifi, briefly, a pair of bi-metallic members each havin one end anchored in a di-electric base and disposed, upon a rise in temperature, to bend toward each other. The unsecured portions of the bi-metallic members are each bent to a Ll-shape with one U enclosing the other and have their free ends bent toward each other andmt d, Upon a, rise in temperature, the free 6 ends of the bi-metallic members move toward each other and longitudinally with respect to each other. When this occurs the pointed end of each of the members contacts with and scrapes along the other member, thus, insuring a good electric contact by scraping off the dust and dirt on the other member. There being two pointed ends, there is thus a double chance of forming an electric contact.

Another feature of our invention is that we provide an improved housing for the bi-metallic members which, while permitting a free circulation of heat therethrough, affords protection for the members against foreign accumulations, such as paint from spray gun, etc.

Apparatus embodying features of our invention 7 is illustrated in the accompanying drawing forming a part of this application, in which Fig. 1 is. a bottom plan view of a device made in accordance with our invention, with the cover removed;

Fig. 2 is aview similar to Fig. 1 showing the bimetallic members in the position they assume responsive to heat, and also showing in diagrammatic form an electric alarm circuit associated therewith;

Fig. 3 is a sectional view taken along the line III--III of Fig. 1 and showing the. housing cover in place; and.

Figs. 4 and 5 are sections taken along the lines IVIV and VV respectively, of Fig. 1.

Referring to the drawing for a better understanding of our invention, We show a housing comprising grilled side walls 10, a grilled bottom 11 and end walls 12 and 13, the end walls being turned outwardly to form fastening lugs 14 and 9 16. The end wall 13 is provided with an elongated opening 17 in which is seated a di-electric base 18, the latter having a flange 19 fitting over the edge of the opening 17. The base 18 is preferably made of some such material as hard rub- 95 her, bakelite or other similar product.

The base 18 is provided with a pair of spaced polygonal holes 21 in which are seated a pair of terminals 22 having shanks fitting in the holes and flanges 23 extending over the edges of the holes 21. The outer ends of the terminals 22 are reduced in size to form threaded screws and a dielectric plate 24 is fitted over them. 'Nuts 26 are screwed on the outer ends of the terminals 22 to, 105 hold them tightly in place and draw the plate 24 and base 19 into tight engagement with the housing. After they are tightened up, the ends of the terminals 22 are headed over to, prevent loosening. Preferably also, clips 27 are provided on 11b the terminals for securing electric conductors thereto.

The inner ends of the terminals 22 are split at 28 and 29. Secured in the slits 28 and 29 are a pair of bi-metallic members 31 and 32. The bimetallic member 31 extends inwardly of the housing and is bent over at 33 toward the bimetallic member 32 into a U-shape with its free end 34 pointed and bent outwardly toward, but out of contact with the bi-metallic member 32. The bi-metallic member 32 is also bent over to form a U enclosing the bi-metallic member 31 and has its free end 37 pointed and bent inwardly toward the bi-metallic member 31.

The provision of the base 18 with the spaced polygonal holes with the shanks of the terminals 22 seated therein insures the uniform spacing of the bi-metallic members when the device is assembled and also prevents the members from being turned upon tightening up the nuts 26.

Upon the rise in temperature to a sufficient degree, such as upon exposure to the heat of fire in a room, the free end 37 of the bi-metallic member 32 moves inwardly to contact with the bimetallic member 31 and downwardly with respect to its normal position as seen in Fig. 2, thereby and 43.

scraping along the surface of the bi-metallic member 31 to form an electric contact. At the same time, the free end 34 of the bi-metallic member 31 moves outwardly to contact with the bi-metallic member 32 and upwardly, scraping along the surface thereof, also to form an electric contact. In this position also the pointed end 3'7 bearing against the member 31 forces it tightly against the inner side of the member 32.

An electric alarm circuit 38 is connected to the terminals 22 which, upon being completed in the manner described, serves to actuate a gong 39 or other suitable alarm devices, not shown. It will thus be seen that the electric circuit may be completed by either the bi-metallic member 31 or the bi-metallic member 32, or both, and that the scraping action of the free ends 34 and 37 insures a contact and a sounding of the alarm even if there be a considerable accumulation of foreign matter on the bi-metallic members.

In order to permit access to the housing for the purpose of possible adjustment of the bi-metallic members 31 and 32, we provide a cover 41 for the housing. It is also important that this cover be so constructed that it may not readily be removed by unauthorized persons and we accordingly provide a concealed means for securing the cover in place. The end walls 12 and 13 of the housing have their outer ends bent over to form flanges 42 The cover 41 is provided with an inturned edge 44 adapted to fit under the flange 43, while the other end of the cover is curved inwardly at 46. The cover is also provided with sides 47 which fit over the side walls 10 of the housing. The cover 41 is made of resilient metal der the flange 42. cover may not be removed by hand but must be such as a thin sheet metal stamping whereby, upon being assembled, it bends and is snapped into place with the curved portion 46 passing un- With this arrangement the pried loose. In order to provide a means for removing the cover, we provide a hole 48 in the end wall 12 in which a pointed instrument, such as a screw driver or punch, may be inserted to pry the lid oil the housing.

From the foregoing description it will be apparent that we have devised an improved automatic fire alarm which is simple of design and construction and reliable in operation, and one wherein an electric contact is assured even with an accumulation of dirt or foreign matter on the contact members.

While we have shown our invention in but one form, it will be obvious to those skilled in the art that it is not so limited but is susceptible of various changes and modifications, without departing from the spirit thereof, and we desire, therefore, that only such limitations shall be placed thereupon as are imposed by the prior art or as are specifically set forth in the appended claims.

What we claim is:

1. In an automatic fire alarm, a pair of bimetallic strips each secured at one end adjacent the other; and being so disposed that the free ends bend toward each other and touch to form an electric contact upon a rise in temperature, the unsecured portion of both strips being bent into a U-shape with one U enclosing the other, and each having its free end bent toward the other bi-metallic strip.

2. In an automatic fire alarm, a pair of bimetallic strips each secured at one end adjacent the other, and. being so disposed that the free ends bend toward each other and touch to form an electric contact upon a rise in temperature, the unsecured portion of both strips being bent into a U-shape with one U enclosing the other, and each having its free end pointed and bent toward the other bi-metallic strip.

3. In an automatic fire alarm, a (ii-electric base member having a pair of polygonal spaced holes, a pair of metallic holders secured in said holes, a pair of bi-metallic members each having one end secured in one of the holders and so disposed that their unsecured portions bend toward each other upon a rise in temperature to touch and form an electric contact, said unsecured portions being bent to a U-shape with one U enclosing the other, the free end of each of said bi-metallic members being formed into a point and bent toward the other bi-metallic member.

4. In an automatic fire alarm, a di-electric base member having a pair of polygonal spaced holes, a pair of metallic holders secured in said holes, a pair of bi-metallic members each having one end secured in one of the holders and so disposed that their unsecured portions bend toward each other upon a rise in temperature to touch and form an electric contact, said unsecured portions being bent to a U-shape with one U enclosing the other, the free end of each of said bi-metallic members being formed into a point and bent toward the other bi-metallic member, a grilled housing for the bi-metallic members in which the base member is seated, a cover for the housing, and concealed means for securing the cover in place.

5. In an automatic fire alarm, a di-electric base member having a pair of polygonal spaced holes, a pair of metallic holders secured in said holes, a pair of bi-metallic members each having one end secured in one of the holders and so disposed that their unsecured portions bend toward each other upon a rise in temperature to touch and form an electric contact, said unsecured portions being bent to a U-shape with one U enclosing the other, the free end of each of said bi-metallic members being formed into a point and bent toward the other bi-metallic member, a grilled housing for the bi-metallic members in which the base member is seated,

and having an opening therein on one side there- 159 of, a resilient cover for the housing having one end adapted to fit under one edge of the opening, and a curved over portion on the opposite end of the cover adapted to bear against and be sprung under the other edge of the opening.

6. In an automatic fire alarm, a grilled casing having an inwardly flanged opening for a cover, a resilient metallic cover for the casing having one edge adapted to extend under one flange of the opening and the opposite edge curved inwardly to be sprung under the opposite edge, a di-electric base at one end of the casing, a pair of spaced terminals seated in the base, and a pair of bi-metallic members each having one end secured in one of the terminals and so disposed as to bend toward each other and touch to form an electric contact upon being subjected to heat, the unsecured ends of both bi-metallic members being bent over and toward each other to provide a scraping contact when heated.

CLIFFORD E. COLE. EARL MORRISON. ISAAC V. SIGSBEE. 

